Remote LFA support for LDP in IS-IS

You can configure a remote loop-free alternate (LFA) to extend the backup provided by the LFA in an IS-IS network. This feature is useful especially for Layer 1 metro-rings where the remote LFA is not directly connected to the PLR. The existing LDP implemented for the MPLS tunnel setup can be reused for the protection of IS-IS networks and subsequent LDP destinations, thereby eliminating the need for RSVP-TE backup tunnels for backup coverage. To configure remote LFA over LDP tunnels, include the remote-backup-calculation statement at the [edit protocols isis backup-spf-options] hierarchy level and the auto-targeted-session statement at the [edit protocols ldp] hierarchy level.